A typical fuel cell system includes a power section in which one or more fuel cells generate electrical power. A fuel cell is an energy conversion device that converts hydrogen and oxygen into water, producing electricity and heat in the process. Each fuel cell unit may include a proton exchange member (PEM) with gas diffusion layers on either side of the proton exchange member. Anode and cathode catalyst layers are respectively positioned between the gas diffusion layers and the PEM. This unit is referred to as a membrane electrode assembly (MEA). Separator plates (also referred to herein and flow field plates or bipolar plates) are respectively positioned on the outside of the gas diffusion layers of the membrane electrode assembly. This type of fuel cell is often referred to as a PEM fuel cell.
The reaction in a single MEA typically produces less than one volt. Therefore, to obtain operating voltages useful in most applications, a plurality of the MEAs may be stacked and electrically connected in series to achieve a desired voltage. Electrical current is collected from the fuel cell stack and used to drive a load. Fuel cells may be used to supply power for a variety of applications, ranging from automobiles to laptop computers.
The efficiency of the fuel cell power system depends on the flow of reactant gases across the surfaces of the MEA as well as the integrity of the various contacting and sealing interfaces within individual fuel cells of the fuel cell stack. Such contacting and sealing interfaces include those associated with the transport of fuels, coolants, and effluents within and between fuel cells of the stack. Proper sealing of fuel cell components and assemblies within a fuel cell stack is critical to ensure efficient operation of the fuel cell system.